The present invention relates to an improved treatment of sludge which comprises biological aggregate which is used for the treatment of drainage etc., more particularly it relates to improve filtering characteristics of the sludge.
The consideration for preventing environmental pollution has been discussed and the control of the drainages has been severe and various drainage treatments have been carried out.
The microorganism treatment of the drainages is indispensable for the treatment of the drainage containing organic materials. The microorganism treatment has been widely applied for various treatment of industrial waste and for removement of nitrogen sources which cause nutritious water in lakes or red sea water. Thus, the microorganism treatments have been developed.
The microorganism treatment has been considered to be remarkably advantageous and has been widely applied, however serious problem has been caused. The problem is the treatment of the proliferated microorganism. In the drainage treatment, the sludge caused by the proliferated microorganism treatment is called as excess sludge to be discharged out of the system.
The discharge sludge containing the microorganism is pasty and tacky material which has high water content and is dehydrated and burnt or used in the reclamation or for other purposes.
However, it has been difficult to dehydrate the sludge by a filtration etc. because of tackiness. Accordingly, the treatment has been unsatisfactory and the treated sludge contains relatively high water content and serious disadvantage has been found for the further treatment.
Various treatments have been proposed to improve the dehydration of the sludge such as by an addition of lime, ferric chloride, polyaluminum chloride, polymer coagulants etc. before the filtration.
However, the effects are not satisfactory and impart slight decrease of the load of the filter etc. or cause other troubles. The problem has not been satisfactorily dissolved.